Question

Given: quadrilateral MNOL with MN ≅ LO and ML ≅ NO

Prove: MNOL is a parallelogram.



Complete the paragraph proof.
We are given that MN ≅ LO and ML ≅ NO. We can draw in MO because between any two points is a line. By the reflexive property, MO ≅ MO. By SSS, △MLO ≅ △. By CPCTC, ∠LMO ≅ ∠ and ∠NMO ≅ ∠LOM. Both pairs of angles are also , based on the definition. Based on the converse of the alternate interior angles theorem, MN ∥ LO and LM ∥ NO. Based on the definition of a parallelogram, MNOL is a parallelogram

Answer 1

1. ONM

2. NOM

3. alternate interior angles

Answer 2

The answers are ONM, NOM, and alternate interior angles.
Based on the SSS postulate, the two triangles △MLO and △ONM are congruent since three sides of △MLO are respectively equal to the three sides of △ONM.
Based on CPCTC, all of the corresponding angles of △MLO and △ONM are congruent as well since the two triangles are congruent, that is,
∠LMO≅∠NOM and ∠NMO≅∠LOM.
Since the pair ∠LMO and ∠NOM as well as ∠NMO and ∠LOM are angles on the inner side of two lines but on opposite sides of the transversal MO, these pairs of angles are also alternate interior angles.